Method and apparatus for controlling an engine based on a target pressure curve

ABSTRACT

An illustrative example method of controlling an engine of a vehicle, includes determining a target pressure curve for a cylinder of the engine, determining a heat release model for the cylinder, determining a mass flow of fuel from the heat release model to achieve the target pressure curve, and automatically controlling opening of an injector of the cylinder of the engine to provide the determined mass flow of fuel to the cylinder.

TECHNICAL FIELD

The present disclosure relates to a method of controlling an engine of avehicle, a control unit and in particular, but not exclusively, to acontroller and a method for controlling a vehicle engine or an enginecomponent such as a cylinder based on a target pressure curve. Aspectsof the invention relate to a method, a controller, and a vehicle.

BACKGROUND

It is generally known that engines have to be controlled by controlunits and that control may depend on engine status. For example, onepart of the control of an engine of a vehicle is focused on theinjection of gasoline or diesel into the combustion chamber of thecylinders of the engine. Some known methods include using specificdiagrams or maps, which comprise specific correlations between theengine status and the respective needed injection timing. To providesuch specific diagrams or maps, significant time and expense istypically needed to build up the specific diagrams or maps fromexperiments and test drives. After gathering sufficient information anddata from such test drives and experiments, specific correlations mustbe determined to provide a simulation model for the engine or thecylinders. The resulting particular diagrams or maps are then used for acontrol method.

SUMMARY

According to an aspect of the present invention there is provided amethod of controlling an engine of a vehicle. The method includesdetermining a target pressure curve for a cylinder of the engine,determining a heat release model for the cylinder, determining a massflow of fuel from the heat release model to achieve the target pressurecurve, and automatically controlling opening of an injector of thecylinder of the engine to provide the determined mass flow of fuel tothe cylinder.

According to another aspect of the present invention there is provided avehicle engine controller comprising at least one processor and datastorage associated with the at least one processor. The processor isconfigured to: determine a target pressure curve for a cylinder of theengine, determine a heat release model for the cylinder, determine amass flow of fuel from the heat release model to achieve the targetpressure curve, and control opening of an injector of the cylinder ofthe engine to provide the determined mass flow of fuel to the cylinder.

According to another aspect of the present invention there is provided avehicle comprising an engine having a plurality of cylinders, aplurality of fuel injectors respectively associated with the cylinders,and a controller comprising at least one processor and data storageassociated with the processor. The processor is configured to: determinea target pressure curve for at least one of the cylinders of the engine,determine a heat release model for the cylinder, determine a mass flowof fuel from the heat release model to achieve the target pressurecurve, and control opening of one of the injectors to provide thedetermined mass flow of fuel to the cylinder.

Within the scope of this application it is expressly intended that thevarious aspects, embodiments, examples and alternatives set out in thepreceding paragraphs, in the claims and/or in the following descriptionsand drawings, and in particular the individual features thereof, may betaken independently or in any combination. That is, all embodimentsand/or features of any embodiment can be combined in any way and/orcombination, unless such features are incompatible. The applicantreserves the right to change any originally filed claim or file any newclaim accordingly, including the right to amend any originally filedclaim to depend from and/or incorporate any feature of any other claimalthough not originally claimed in that matter.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described by theway of example only with reference to the accompanying drawings, inwhich:

FIG. 1 shows a schematic view of an inventive vehicle,

FIG. 2 shows a schematic view of an inventive control unit designedaccording to an embodiment of this invention,

FIG. 3 illustrates an example target pressure curve,

FIG. 4 schematically illustrates an example injector profile and

DETAILED DESCRIPTION

FIGS. 1 and 2 schematically illustrate selected portions of a vehicle200. An engine 100 has a plurality of cylinders 110. Four cylinders 110are illustrated for discussion purposes and the number of cylinders ofthe engine 100 may be different depending on the particular vehicle. Afuel injector 112 is associated with each cylinder 110 for providingfuel to the corresponding cylinder 110. The fuel injectors 112 compriseknown component arrangements including, for example, an injector valve.

An on-board vehicle controller or engine controller 300 includes atleast one processor that is particularly configured to carry out acontrol method for achieving a desired operation or function of thecylinders 110 by controlling the fuel injectors 112. The controller 300also has data storage associated with the processor. For discussionpurposes, portions of the processor and data storage are collectivelyrepresented in FIG. 2 at 310, 320 and 330. The data storage may be apart of the device in which the controller 300 is embodied (asschematically illustrated in FIG. 2) or it may be accessible by theprocessor or other portions of the controller 300 so that programmingand information in the data storage may be used by the processor on anas needed basis. In one example, the data storage includes programmingthat the processor uses to carry out the control methods and features ofthe disclosed embodiment.

As schematically represented in FIG. 2, the controller 300 includesthree main modules, which may be realized through hardware, firmware,software or a combination of these. The first module schematically shownat 310 is a curve and model determination module that provides, in part,a target pressure curve for a particular one of the cylinders 110. Thetarget pressure curve indicates desired pressures within the cylinder110 associated with combustion rates during a working cycle of thecylinder 110.

An example target pressure curve 10 is shown in FIG. 3. The targetpressure curve 10 is defined in terms of a crank angle, which is relatedto movement of the piston of that cylinder) on the x-axis and thepressure within the cylinder on the y-axis. In the illustrated example,after about 60° the pressure essentially plateaus until an increasebegins at a point which can be referred to as the start of ramp. As hasbeen determined in other contexts, the start of ramp is almost equalwith the start of the combustion within the combustion chamber. Due tothat combustion, the pressure rises even more along that ramp and theramp follows the ramp angle α. After the piston is pushed back by thecombustion and the increase of the pressure within the cylinder 110, thepressure curve declines as shown on the portion in FIG. 3 leading to theend of the target pressure curve 10 for a single working cycle of thecylinder 110.

One feature of this invention is that it facilitates selecting the startof ramp and the value (or range) of the ramp angle α prior to theworking cycle of the cylinder 110 in a predictive, feed forward mannerto optimize the combustion process. By optimizing the combustion processin this way, better efficiency is achievable in terms of noise andpollutant emission. For example, in diesel engine embodiments, resultantnoise is strongly correlated with the maximum in-cylinder pressuregradient and controlling or selecting the value of ramp angle α providescontrol over the combustion noise. The start of combustion influencesrotational imbalance of the engine 100 and, therefore, controlling orselecting the start of ramp indirectly provides control over combustionnoise. The centroid of cumulated combustion heat release is a strongindicator of combustion efficiency is influenced by the start of rampand the ramp angle α so controlling either or both according to anembodiment of this invention facilitates improved efficiency.

According to the illustrated example embodiment, the start of ramp andramp angle α are controlled so that the in-cylinder pressure gradientcorresponds to a desired combustion sound level threshold while theresulting combustion centroid remains as close as possible to itsoptimum position. The controller 300 achieves the resulting optimumin-cylinder pressure trace by adjusting the fuel injection profileaccordingly. In this embodiment, the controller 300 adapts the injectorprofile for any change in rail pressure and, therefore, decouples thein-cylinder pressure gradient from the rail pressure. This allows forrail pressure and air entrainment increases without generating drawbacksin the combustion sound level. In other words, the pressure gradientand, therefore, the combustion rate, is controlled independently ofadjusted rail pressure, which enables decoupling the soot-noisetrade-off. Controlling the ramp angle α according to this embodimentcombines low soot emission with low combustion sound levels.

There have been feedback, iterative approaches that have demonstratedthe usefulness of controlling the so-called Alpha-Process but theysuffer from the drawbacks of requiring significant processing capacityand difficulty in achieving a quick enough response to provide a targetcurve for a subsequent working cycle of a cylinder before the enginecondition or status changes. One challenge associated with controllingvehicle engines using such an approach is that the engine status isvariable and different conditions yield differing results.

The curve and model determination module 310 determines the targetpressure curve in a feed forward manner in the time between a previouscombustion cycle and the combustion cycle in which the control will beutilized. The controller 300 ultimately predicts the full injectionprofile including the number of injections, the injection timing and theinjection valve energizing durations, which result in the desiredcombustion rate. A feature of the controller 300 is that it determinesin-cylinder gas state traces before the onset of the actual workingcycle.

The curve and model determination module 310 in some embodiments usesengine map data that is obtained in a known manner to determine thedesired start of ramp and ramp angle α. Map data may be predeterminedfor a variety of engine conditions and the pressure curve determinationmodule obtains an indication of the engine condition or status to beable to select the appropriate map data for setting the target pressurecurve. The map data in some embodiments corresponds to a thermodynamicengine model. The example approach keeps computation requirements lowfor predicting the required injection profile. Additionally, differentengine configurations may benefit from the same map data as it isthermodynamic-model-based. It is also possible to address issues likecomponent wear and fuel differences through a learning mechanismdirectly adapting the affected combustion model parameter.

The engine map data is based on in-cylinder gas states that aredetermined along the crank angle axis from IVC till EVO timings. Thein-cylinder gas state at IVC is well known from mean-value cylinderfilling models, which consider the EGR strategy, and the charge airconditions. The target pressure curve 10 is determined in one examplebased on a desired start of ramp and angle of ramp using polytropiccompression from IVC until start of ramp followed by constant pressureincrease according to the ramp angle alpha until the end of ramp andthen polytropic expansion from the end of ramp until EVO. Experimentalor empirical data may be used to confirm or develop the engine map data.

The curve and model determination module 310 also determines a heatrelease model 20. This model is based on a difference between thecumulated injected fuel energy is ready for conversion after ignitiondelay and the heat energy that has already been released for each sampletime t within the combustion cycle. This energy difference representsthe maximum potential for instantaneous heat release and can thereforebe correlated with the current burn rate. The maximum heat releasingpotential cannot be fully used, however, because of a limited mixingrate of fuel and air. The heat release model 20 includes a combustionrate factor to scale down the maximum heat releasing potential. In oneembodiment, the combustion rate factor describes the rate with which thecurrent maximum heating potential can be converted and may be in unitsof 1/second.

The heat release model 20 includes an ignition delay as a state variableand the combustion rate factor as a calibration parameter. The ignitiondelay indicates a correlation between the fuel conversion and thehydraulic fuel injection. For example, a longer ignition delay resultsin a higher amount of unburned fuel energy introduction and a higherfuel air mixture. This results in an increased maximum heat releasingpotential. Accordingly, the heat release model 20 includes an increasefor higher ignition delay.

Using a continuous combustion rate factor correlated to the burn rateallows a very accurate prediction of the burn rate for a given injectionprofile. Accordingly, a fuel injection rate can be accurately predictedfor a determined burn rate. In the illustrated embodiment, the heatrelease model 20 and the target pressure curve 10 are provided to adetermination module 320 which is now able to take into account thecorrelation of the heat release model 20 and determines the mass flow 30of fuel which is needed to achieve the target pressure curve 10. Thatmass flow 30 can be considered in terms of a mass flow curve that isresolved over the crank angle. In one example, the mass flow 30 is basedon an inversion of the heat release model 20 to obtain a converted fuelrate trace profile.

The target value of the feed forward controller 300 is the fuelinjection rate, which is determined by a signal module 330 based on thetarget pressure curve 10 and the heat release model 20. The output fromthe signal module 330 schematically shown at 40 in FIGS. 2 and 4 is aninjector profile 40 comprising control signals 42. The injector profile40 controls the start of energizing and the energizing duration for eachinjection event to be applied to the injection system for a particularinjection cycle. In this example, the injector profile 40 is based onthe inverse of the heat release model and provides a continuoushydraulic injection rate profile.

The injector profile 40 is digitized in some embodiments based on knowninjector behavior characterized by the hydraulic flow rate, minimumhydraulic dwell time, injection duration, and needle opening or closingbehavior. Such characteristics of the injector 112 are known and dependon the configuration of a given injector.

The control signals 42 that give a specific opening time and closingtime for the fuel injector 112 associated with the cylinder 110 ofinterest are determined based on an inversion of the hydraulic injectionprofile. The signals for the opening and closing times can be consideredan electric injection profile. The opening and closing times for eachinjection event may be instants or time periods, depending on the needsof a particular embodiment control of the opening and the closing of theinjector 112.

The embodiments that become apparent from the preceding descriptioninclude feed forward control that is based on determining a desiredsynthetic in-cylinder pressure trace corresponding to the Alpha process.The target pressure curve is a basis for a heat release model, which inturn serves as a basis for a continuous, hydraulic fuel injectionprofile. Digitization allows the fuel injection profile to be used forcontrolling currently available fuel injectors. The predictive controltechnique includes crank angle resolved mean-value models with lowcomputational effort that overcomes the speed of convergence problemsassociated with prior feedback based approaches. The physical modelbased formulation keeps the calibration effort low. The model parametersdirectly refer to geometric and thermodynamic properties that are wellknown for a particular engine configuration.

The provision of a target pressure curve is now the provision of aparameter in form of a target pressure curve which is used to providethe engine with an effect to be achieved, namely a target pressurecurve. It has to be noted that in the broad scope according to thepresent inventive method, the target pressure curve does not need tohave any feedback from a real pressure curve, which is in realityachieved by the inventive method within the cylinder. The targetpressure curve is used as a theoretical forecast, which is the basis forthe control method according to this aspect of the present invention.

The target pressure curve gives no information about specific sensor orcontrol signals, which can be used for the control of the engine. Such acorrelation is established as described above with a heat release modelthat correlates the pressure and heat using time and crank angle for theengine to ensure timely correlation between the differentdeterminations.

Due to the fact that the heat release model is correlated with thepressure within the cylinder as well as with the mass flow of the fuelwithin the cylinder, the correlation of the thermal release is able toform a correlation between the target pressure curve as well as the massflow. Based on that interface which is built up by the thermal releasecorrelation, it is now possible by the method for controlling an engineaccording to this aspect of the present invention to determine the massflow of the fuel from that heat release model to achieve the targetpressure curve in particular theoretically. After having done thatdetermination step, a provision of the determined mass flow is carriedout to control the opening of an injector of that cylinder of theengine.

The injector of a cylinder can, for example, be an injector valve or anyother kind of valve enabling fuel to enter the combustion chamber of thecylinder. The opening of that injector leads to a mass flow of fuelentering that cylinder. The closing of that injector stops that massflow of fuel.

As it can be derived from the preceding description, the determined massflow is now one possibility to offer control signals to the opening andclosing of the injector of that cylinder. Therefore, now a controlmethod is given by this aspect of the present invention which enables aprovision of a target pressure curve and translates that target pressurecurve by the use of a heat release model into control signals to achievea determined mass flow. Feedback from the cylinder about the realachieved pressure curve is not necessary to carry out that method.

As it can be derived from the preceding description, no or at least noexperiment or test drive has to be carried out to use the disclosedcontrol method. The target pressure curve can be provided, for example,from a specific diagram or map or as one single standard target pressurecurve for all different status of the engine. Of course, it is alsopossible to provide different target pressure curves for differentsituations of the engine.

Beside the reduction of cost and time for establishing the basis for thecontrol method, even the quality of the control itself is increased bythe inventive method. Due to the fact that a correlation using the heatrelease model is used within the inventive method, now an online andreal time control is possible within the engine itself. Therefore,beside the fixed specific diagrams or maps from the state of the art nowa much higher flexibility can be used within the inventive controlmethod.

Due to the fact that the method according to this aspect of the presentinvention does not need any feedback information, it can also bedescribed as a method for pre-control of an engine of a vehicle. Theprovision of the target pressure curve can also be defined as aprovision of a synthetic pressure curve.

The injector control signals in some embodiments specifically take intoaccount the mechanical and real possibilities of the injector itself.Therefore, specific control signals can be provided by the inventivemethod according to this aspect of the present invention, which can beused in the control of the engine of the vehicle. In the case of theinjector being configured as an injector valve, such an injector profilecan be embodied as an electric fuel injection profile. Such an injectorprofile can be configured to adapt the present method to different kindsof engines. Therefore, the method can be provided generally and can bespecified by the provision of a respective engine specific injectorprofile.

It is further possible that according to an aspect of the presentinvention the method is characterized in that the injector profile iscorrelated with a digital injector procedure of the injector. Aninjector procedure in a digital manner has to be understood that theinjector is in a mechanical real way only possible to open and close.There is no possibility of such an injector to regulate or controlspecific and different amounts of mass flow passing that injector. Itcan, for example, be considered to be an opening and closing valve incontrast to a continuous controllable valve. A digitalization stepaccording to this aspect leads to a further reduction of complexity inparticular with respect to the mechanical construction of the injectoritself. No quantitative opening or closing has to be consideredaccording to this aspect of the present invention. The determined massflow rate can be digitalized by a hydraulic fuel injector model. Such amodel can generate a corresponding, digital fuel injection profile,taking into account fuel injector hardware specific boundary conditions,such as minimum dwell time or minimum injection quantities/energizingdurations. Further it is possible that the fuel injector model generatesthe corresponding electric actuation signal, consisting of a number ofinjections, injection timings and/or energizing durations for eachinjection event. Thus, a control unit, carrying out an inventive method,is capable in determining the full electric injection profileautomatically.

It is also possible that according to an aspect of the present inventionthe method is characterized in that the injector profile is correlatedwith a continuous injector procedure of the injector. In contrast to theaspect discussed in the paragraph above, it is possible to have a morecomplex injector comprising the possibility of a quantitative control.Due to the fact that the injector profile now comprises the informationof that continuative possibility of the injector, this can be taken intoaccount so that, for example, respective control signals can beconfigured to fit to that continuous injector procedure of the injector.Such a continuous mass flow can for example be realized by a rateshaping capable fuel injector as an injector. An injector model cancalculate the corresponding electric injector actuation signals.

A further possibility is achieved according to an aspect of the presentinvention wherein the method is characterized in that the targetpressure curve is provided in dependence of the engine operation point,the engine status and/or the cylinder status. Beside the generalpossibility that one single target pressure curve is used for allcontrol steps according to the inventive method it is also possible thatone or even more different target pressure curves are used. Thedependency as to the engine status and/or the cylinder status can forexample be focused on the load situation of the engine, the engineoperation point (rotational speed, load, . . . ), engine mode (normal,regeneration of particle filter, . . . ) and/or the engine condition(engine temperature, ambient temperature, . . . ). For example, adifference can be expected for a full load situation, a part loadsituation, a fuel saving mode for the engine or the like. The dependencycan, for example, be stored in a respective specific characteristicdiagram or map, giving a specific and easy as well as fast correlationbetween the status of the engine and/or the cylinder and the respectivetarget pressure curve to be used. This leads to an even betteradaptation to different load situations of the engine. Also engine loadinformation like the mean indicated pressure can be inherited in thetarget pressure curve. Beside the use of the respective status for thetarget pressure curve, that information can also be used for furthersteps of an inventive method. This could be for example the number ofinjections/valve openings, timing of such injections/openings,energizing durations, are determined in particular for each injectionevent.

It is further possible that according to an aspect of the presentinvention the method is characterized in that the provision of thetarget pressure curve comprises at least two iterations, when the targetpressure curve is optimized as to at least one parameter. Beside theaspect discussed in the paragraph above, it is also possible to carryout an optimization within the inventive method. This leads to apossibility to consider two or more iterations and considering theoptimization of a parameter. Such a parameter can for example be aparameter of the pressure curve itself, for example a ramp angle named aor at a point at which this ramp starts, namely the start of ramp SOR.It is preferred that the length of the ramp is optimized to achieve apredefined mean pressure. The iterations can for example be focused on aparameter like a mean pressure of the respective cylinder. This leads tothe possibility that the basis or the starting point of the presentcontrol method is optimized as to the specific situation within theengine. This leads to further accuracy when achieving efficient controlof the engine and the cylinder. It has to be noted that this is apre-optimization and not a feedback control.

According to a further aspect of the present invention, the method ischaracterized in that the heat release model comprises a variablecombustion factor, wherein the combustion factor is in particulardependent from at least one engine parameter. These variable combustionfactors are in contrast to the commonly known fixed combustion factorsvariable in particular dependent from a respective parameter of theengine. One of those parameters can, for example, be the crank anglesuch that now the combustion factor can take into account the crankposition as to the crank angle. This leads to a better real timeadaption during the process of the combustion inside of the cylinder. Italso allows a better correlation of the target pressure rate and the aimto achieve an efficient control of the engine.

According to an aspect of the present invention, for a pre-controland/or a control concept a heat release model can be used to link thefollowing two domains: the hydraulic fuel injection profile (includinginjection timings, injection quantities and number of injections) andthe corresponding in-cylinder combustion rate, i.e. heat release and/orburn rate. However, one single hydraulic fuel injection profile canresult into a variety of different in-cylinder combustion rates,depending on the current in-cylinder condition. To characterize thecurrent in-cylinder condition, the so called “combustion factor” can beintroduced, which accounts for e.g. level of turbulence, temperature-and pressure level. Thus, the combustion factor is required to beformulated in dependency of the engine operation point and the enginecondition. Further, the in-cylinder condition changes within the courseof the combustion. Therefore, the combustion factor can generally bevariable within the combustion progress. Some embodiments includeidentifying an individual combustion factor value for each crankangleposition within the combustion process. This is the reason why thecombustion factor can be considered as a trace, rather than a singlevalue. Summarizing, the combustion factor can be considered as aparameter to adjust the combustion reaction for a given fuel injectionprofile.

It is a further aspect of according to the present invention that themethod is characterized in that the combustion factor comprises acombination factor combining at least two different combustion types.For example, a combustion type can be a diffusive combustion and/or amixed combustion. Based on the combustion type, different combustionfactors can be taken into account. Using a combination factor, a shiftbetween the different combustion types can be carried out during thedetermination step of the mass flow of the fuel. This leads to an evenfurther better adaptation for the target pressure curve. Such acombustion factor can generally be used as variable with respect to thecrank angle during the combustion progress. Calculation of thecombustion factor can take into account diffusive, premixed and mixedcombustion stages.

The invention claimed is:
 1. A method of controlling an engine of avehicle, the method comprising: determining a target pressure curve fora cylinder of the engine; determining a heat release model for thecylinder; determining a mass flow of fuel from the heat release model toachieve the target pressure curve; and automatically controlling openingof an injector of the cylinder of the engine to provide the determinedmass flow of fuel to the cylinder.
 2. The method according to claim 1,comprising determining an injector profile based on the determined massflow of fuel, the injector profile comprising an opening time and aclosing time for the injector.
 3. The method according to claim 2,wherein the injector profile comprises control signals for opening andclosing the injector.
 4. The method according to claim 2, comprisingcorrelating the injector profile with a digital injector procedure ofthe injector.
 5. The method according to claim 2, comprising correlatingthe injector profile with a continuous injector procedure of theinjector.
 6. The method according to claim 1, comprising determining thetarget pressure curve based on at least one of an operation point of theengine, a status of the engine and a status of the cylinder.
 7. Themethod according to claim 1, wherein determining the target pressurecurve comprises at least two iterations; and the target pressure curveis optimized as to at least one parameter.
 8. The method according toclaim 1, wherein the heat release model comprises a variable combustionfactor; and the combustion factor is based on at least one engineparameter.
 9. The method according to claim 8, wherein the combustionfactor comprises a combination factor combining at least two differentcombustion types.
 10. A vehicle engine controller, comprising at leastone processor and data storage associated with the at least oneprocessor, the processor being configured to: determine a targetpressure curve for a cylinder of the engine; determine a heat releasemodel for the cylinder; determine a mass flow of fuel from the heatrelease model to achieve the target pressure curve; and control openingof an injector of the cylinder of the engine to provide the determinedmass flow of fuel to the cylinder.
 11. The vehicle engine controlleraccording to claim 10, wherein the at least one processor is configuredto determine an injector profile of the injector based on the determinedmass flow of fuel, the injector profile comprising an opening time and aclosing time for the injector.
 12. The vehicle engine controlleraccording to claim 11, wherein the injector profile comprises controlsignals for opening and closing the injector.
 13. The vehicle enginecontroller according to claim 11, wherein the at least one processorcontrols a digital injector procedure of the injector, the digitalinjector procedure being correlated with the injector profile.
 14. Thevehicle engine controller according to claim 11, wherein the at leastone processor controls a continuous injector procedure of the injector,the continuous injector procedure being correlated with the injectorprofile.
 15. The vehicle engine controller according to claim 10,wherein the at least one processor determines the target pressure curvebased on at least one of an operation point of the engine, a status ofthe engine and a status of the cylinder.
 16. The vehicle enginecontroller according to claim 10, wherein the at least one processordetermines the target pressure curve using at least two iterations; andoptimizes the target pressure curve as to at least one parameter. 17.The vehicle engine controller according to claim 10, wherein the heatrelease model comprises a variable combustion factor; and the combustionfactor is based on at least one engine parameter.
 18. The vehicle enginecontroller according to claim 10, wherein the combustion factorcomprises a combination factor combining at least two differentcombustion types.
 19. A vehicle comprising: an engine having a pluralityof cylinders; a plurality of fuel injectors respectively associated withthe cylinders; and a controller comprising at least one processor anddata storage associated with the processor, the at least one processorbeing configured to: determine a target pressure curve for at least oneof the cylinders of the engine; determine a heat release model for thecylinder; determine a mass flow of fuel from the heat release model toachieve the target pressure curve; and control opening of one of theinjectors to provide the determined mass flow of fuel to the cylinder.20. The vehicle of claim 19, wherein the at least one processor isconfigured to determine an injector profile of the one of the injectorsbased on the determined mass flow of fuel, the injector profilecomprises an opening time and a closing time for the injector; and theinjector profile comprises control signals for opening and closing theinjector.